Disposable absorbent products (e.g. disposable diapers, sanitary napkins, and the like) generally contain absorbent webs of wood pulp fibers. Depending on the climate, it takes a tree from about twenty years to about forty years to mature to a harvestable state. Consequently, in order to meet the demands for wood pulp fibers to be used in absorbent materials, vast areas of land are necessary for the growing of trees. As another consequence, even though wood pulp fibers are probably the most economical materials used in disposable absorbent products available today, substantial expenditures are made in harvesting and growing of the trees. There is, therefore, a continuing need for alternative, inexpensive, absorbent materials, preferably from renewable resources.
It has now been discovered that certain pectin-containing agricultural byproducts can be converted to highly absorbent materials, suitable for use in disposable absorbent products, via a relatively simple and inexpensive process. Typical examples of agricultural byproducts suitable as raw materials for the absorbent materials of the present invention include the residue materials from citrus juice processes and from sugar beet refineries. These materials are abundantly available at low cost. Pectin-containing agricultural residue material can be converted to a highly absorbent material by introducing into the materials sufficient anionic groups as to obtain a cation exchange capacity of from about 0.5 meq/g to about 6 meq/g of the vegetable material. The vegetable-derived absorbent materials typically have an absorbent capacity which is from two to five times that of conventional wood fiber webs. These materials, therefore, offer an opportunity to reduce the bulk of absorbent products while maintaining their containment capacity.
It is, therefore, the object of this invention to provide an inexpensive, absorbent material suitable for use in disposable absorbent products. It is another object of this invention to provide a process for converting certain pectin-containing agricultural waste materials to the absorbent materials of this invention.
It is a further object of this invention to provide absorbent structures which comprise, in addition to a conventional absorbent material, the novel absorbent material of the present invention. It is also an object of the present invention to provide disposable absorbent products, like disposable diapers and sanitary napkins, comprising the absorbent vegetable materials and absorbent structures of the present invention.